A case is reported of a 72 year old man suffering from classical seropositive RA for 10 years. Two months before admission he experienced general illness, fever and itching. Lymph nodes enlargement and hepatosplenomegaly were found. Histologic features of lymph node biopsy were compatible with angioimmunoblastic lymphadenopathy and Lennert lymphoma. Rapidly progressive pulmonary deterioration followed with hilar invasion and honeycombing. Sternal punction, bone biopsy, bronchus biopsy and blind lung biopsy however, did not reveal lymphomatous invasion. On the contrary, lung biopsy, showed bronchiolitis obliterans, an often fatal, small airway disease whose connection with RA is discussed. Plasmapheresis induced a correction of leucopenia and thrombocytopenia. A fatal evolution evolved within six months. Autopsy revealed diffuse invasion by immunoblastic sarcoma. The clinicopathological entities angioimmunoblastic lymphadenopathy and Lennert lymphoma are referred to. The relationship with autoimmune disorders is stressed.